Carbonless manifold business forms

ABSTRACT

Sets of manifold business forms are coated on selected surfaces thereof with chemicals which are capable of reacting with each other to produce a colored mark. In one arrangement at least one intermediate sheet is coated on one surface with a composition of a record-developing material (which is generally solid) and a non-compatible color precursor (which is generally in the form of a microencapsulated liquid) to thereby function as both a record-receiving and a color-transfer surface upon reacting with the coating of at least another separate sheet of the set containing another compatible color precursor and/or another record-developing material on the surface thereof. In another arrangement, some of the sheets are coated front and back with a record-developing material, while others are coated front and back with a microencapsulated color precursor. In each of the arrangements the sheets of the manifolded sets are capable of being so arranged such that by removal of certain parts of the sets or turning certain parts upside down and applying pressure on the backs of the sets, images may be developed on both sides of the sheets.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of co-pending application Ser. No. 561,623, filedNov. 24, 1975, now U.S. Pat. No. 3,981,523.

BACKGROUND OF THE INVENTION:

1. Field of the Invention

The present invention relates generally to a carbonless copying systemwherein mating sheet surfaces are coated respectively with compatibleinitially colorless reactive components capable of reacting to produce acolored mark upon impact. More particularly, the invention relates tomanifold sets utilizing both single and dual initially colorless colorforming systems whereby it is possible to produce a colored mark on bothsides of such sheets by impact.

2. Description of the Prior Art

Manifolded sets of carbonless copying paper normally comprise a topsheet, a bottom sheet and at least one intermediate sheet disposedtherebetween. The top sheet which is conventionally coated on its backsurface with an encapsulated solution of a colorless color-former in asuitable solvent and is generally therefore referred to as CB ("CoatedBack") paper. The bottom sheet conventionally has its front surfacecoated with a solid material containing a record-developing material andthis "front coated" sheet is generally referred to as CF paper. Theintermediate sheets are often coated respectively with theabove-mentioned solid record-developing material in the front coatingsand with the color precursor in the back coatings and accordingly such"front and back coated" sheets are referred to as CFB paper. The backcoatings normally comprise pressure rupturable microcapsules containinga fluid color precursor in fluid form which is capable of reacting tothereby form a colored compound with the developing material in thefront coating of the next adjacent sheet so that, upon impact by amachine key or application of pressure by a stylus on the top sheet, thecontents of the ruptured capsules in the back coatings spill out andreact with the developing material to form a colored mark on the latterwhich corresponds to the mark impressed by the stylus or machine key.

The present invention relates generally to a copendng and commonly ownedU.S. application Ser. No. 466,910, filed May 3, 1974, and entitled "DUALSYSTEM CARBONLESS PAPER", now abandoned the entirety of the disclosureof which is hereby specifically incorporated herein by reference. Inthis regard it is to be noted that the present application also relatesto dual systems of co-reactive materials; however, the present inventiondiffers from that of the above-mentioned application in its constructionand purpose as will be more clearly brought out hereinafter.

Although, in conventional manifolded carbonless copying sets, the backcoatings normally comprise a microcapsulated solution of the colorprecursor and the front coatings normally comprise a solidrecord-developing material, it should be pointed out that the reverse isalso possible so that the front coatings comprise microcapsules and theback coatings comprise a solid record-developing material. Moreover, theco-reactants may both be microencapsulated liquids. United Statespatents which illustrate various types of systems which may be used inthe production of carbonless transfer papers are, for example, U.S. Pat.No. 2,299,694 to Green, U.S. Pat. No. 2,712,507 to Green, U.S. Pat. No.3,016,308 to Macaulay, U.S. Pat. No. 3,429,827 to Ruus and U.S. Pat. No.3,720,534 to Macaulay et al.

The aforementioned Green (U.S. Pat. No. 2,712,507) and Macaulay (U.S.Pat. No. 3,016,308) patents illustrate the most common variety ofcarbonless impact transfer paper of the type with which the presentinvention is primarily concerned wherein microcapsules containing aliquid fill comprising a chemically reactive color-forming precursor arecoated on the back surface of a sheet, and a dry coating of a solidco-reactant chemical for the precursor is coated on the front surface ofa receiving sheet.

In the current carbonless copying systems of the type aforedescribed theimage is usually developed on the front sides of the sheets. In certaincases, however, it is desirable and advantageous for images to beproduced on both sides of several or all sheets of a set of manifoldbusiness forms. Depending on the particular business needs, varioustypes of entries are required to be made on the sheets of a manifold setof forms thereby requiring larger and more detailed sets of forms to bemade which results in the need for more paper and precise printingtechniques. Carbon transfer sheets have sometimes therefore beeninterleaved with carbonless paper systems so that, after an image isproduced on the front side of the receiving sheet using the carbonlesssystem, an image can also be produced on the back side of such receivingsheet by means of the conventional carbon transfer. The problems ofcarbon smudging, poor manifolding and difficulty in manufacturenevertheless persist in such an arrangement.

An interesting prior art reference in Japanese patent publication No.43-28652. This patent discloses a carbonless duplicating notebookconsisting of a set of initially colorless copying sheets containingpressure rupturable components for transfer of the color formingingredients. The patent is basically directed to a base sheet having afirst color forming reactant on each side thereof. A plurality ofsecondary sheets are provided each of which has one side thereof coatedwith a second color forming reactant reactable with the first colorforming reactant to form a color and the second side thereof coated withthe first color forming reactant. Sets are formed by placing thesecondary sheets on either side of the base film with the second colorforming reactant coated surfaces facing the first color forming reactantsurfaces. However, this patent does not generally disclose the conceptof having an image produced on each side of the sheets of the set.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide acompletely carbonless manifolded set of recording sheets so constructedto permit an image to be developed on both sides of the sheets.

Another object of this invention is to provide such a manifolded setwherein individual sheets may be coated with a mixture of amicroencapsulated color precursor and a record-developing material whichis non-compatible therewith. By itself such a coating cannot present aso-called self-contained sheet since image development cannot occur ifsuch capsule contents and the record-developing material come intocontact. However, such sheets can act both as as a record-receiving CFsheet and as a color-transfer surface CB sheet. Image development maythen be provided by using separate sheets coated with a compatible colorprecursor or record-developing material.

A further object is to provide a manifolded set wherein each sheet iscoated both front and back with a record-developing material and/or witha microencapsulated color precursor.

A still further object of the present invention is to provide such amanifolded set wherein a chemically compatible reaction system isemployed using color precursors and record-developing coatings disposedon selected surfaces of the sheets to facilitate development of an imageon both sides of the sheets.

A still further object is to provide a manifolded set wherein tworeaction systems are employed such that the color precursor of onesystem is chemically incompatible to develop a color with therecord-developing material of the other, and vice versa, although thevarious components of both systems may be coated on selected surfaces ofthe sheets and/or as a mixture on selected surfaces so as to facilitatea wide range of manifolded transfer paper sets capable of producingimages on both sides of the sheets.

Other objects, advantages and novel features of the invention willbecome more apparent from the following detailed description of theinvention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 through 4 are elevational, expanded and enlarged,cross-sectional views of several embodiments of manifolded sets ofcarbonless recording sheets embodying the principles and concepts of thepresent invention; and

FIGS. 1A through 4A are views similar to FIGS. 1 to 4, respectively,showing the arrangement of the sheets for each embodiment to facilitateimage development on the opposite sides thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

The manifolded set of carbonless recording sheets generally designatedby the reference numeral 10 in FIG. 1 includes a top sheet 11, a bottomsheet 12 and several intermediate sheets 13 through 17. The top andbottom sheets 11 and 12 are respectively coated back and front withcoatings 180 and 190, while intermediate sheets 13, 15 and 17 includeback coatings 210. Intermediate sheets 14 and 16 each include frontcoatings 190 and back coatings 180. As shown, each of the sheets 11through 17 are disposed to overlie one another with their back coatingsand front coatings therethroughout normally in contact with one anotherin the manifolded set, although these sheets are shown as beingvertically spaced in FIG. 1 for the sake of clarity. Each of thecoatings 180, 190 and 210 includes at least one color-forming reactivematerial, and the reactive material in each of the back coatings 210 iscapable of reacting with a reactive material in each of the frontcoatings 190, when pressed thereagainst, to produce a colored mark in amanner to be more fully described hereinafter. The reactive material ineach coating 180 is capable of reacting with a reactive material in eachof the coatings 190 when arranged as shown in FIG. 1A for contacttherewith, in a manner to be hereinafter more fully described. However,the reactive materials in coatings 180 and 210 are chemicallyincompatible to form a color.

Although five intermediate sheets are shown in FIG. 1, it should bepointed out that set 10 could include additional intermediate sheetssimilar to 14 or 16 and 13, 15 and 17, and could likewise include as fewsheets as 11, 13 and 12 without departing from the principles andconcepts of the present invention.

The reactive material in each coating 210 comprises a first initiallycolorless reactive component of a first initially colorless reactionsystem. The reactive material in each coating 190 comprises a mixture ofa second initially colorless reactive component of the first reactionsystem and a first initially colorless reactive component of a secondreaction system. Further, the reactive material in each coating 180comprises a second initially colorless reactive component of the secondreaction system. The first and second components of the first system arecapable of interreacting when brought into reactive contact with oneanother, such as by impact, to produce a colored mark. Likewise, thefirst and second reactive components of the second system are capable ofinterreacting when brought into reactive contact with one another toproduce a similar colored mark. On the other hand, the second reactivecomponent of the second reactive system in coatings 180 is notchemically compatible to produce a colored mark when brought intocontact with the first reactive component of the first reactive systemin coatings 210. Further, the second component of the first reactivesystem and the first reactive component of the second reactive system incoatings 190 are not chemically compatible to form a colored mark.

Generally, the reactive components of coatings 210 will be identical.However, it should be pointed out, that the use of a third reactionsystem is possible in that the reactive material in coating 210 of sheet17 might be chemically compatible only with a reactive component of themixture of components in the coating 190 of sheet 12, and notcompatible, for example, with a reactive component of the mixture ofcomponents in coating 190 of intermediate sheets 14 and/or 16.Similarly, sets including more than three different color systems couldbe utilized in connection with the present invention.

FIG. 1 illustrates the manner in which images are transferred onto asurface of several sheets underlying top sheet 11 as pressure is appliedthereto in the direction of arrow 70. Preferably, at least one of themixture of components in coatings 190 is contained in the form of aliquid fill material in tiny rupturable microscopic capsules. This fillcomprises the first reactive component of the second reactive systemdescribed above. The tiny rupturable microcapsules are illustrated assmall circles. Likewise, coatings 210 preferably comprise tinyrupturable microscopic capsules having liquid fill therein, which fillcomprises the first reactive component of the first reactive system.Such microcapsules are also illustrated by small circles. When thecapsules in coatings 210 are ruptured, by the application of pressure bystylus or machine key to the upper surface of sheet 11, as indicated bythe arrow 70 in FIG. 1, a mark 24 may immediately be impressed on topsheet 11 of the set and corresponding marks 25 are formed on the uppersurfaces of sheets 14, 16 and 12 as the fill from coatings 210 of sheets13, 15 and 17 spills out of these ruptured capsules to contact andco-react with the second reactive component of the first reaction systemcontained in the mixture of reactive components of coatings 190 ofcorresponding underlying sheets 13, 15 and 17. Obviously, since the topsurfaces of intermediate sheets 13, 15 and 17 are uncoated, no mark isleft on the surfaces.

Throughout the drawings, the uncapsulated first reactive component ofthe first reactive system is illustrated as a series of small circlescontaining a plus mark + while the first reactive component of thesecond reactive system is illustrated as a series of small circlescontaining an × mark × . The second reactive component of the firstreaction system is illustrated as a series of plus marks (+), while thesecond reactive component of the second reaction system is illustratedas a series of × marks (×).

For producing images on the opposite surfaces of sheets 14, 16 and 12which have been marked, as described above, sheets 13, 15 and 17 areremoved and the set is turned over to form a set 10A illustrated in FIG.1A wherein sheet 12, which was previously the bottom sheet, is now thetop sheet for receiving an impact as illustrated by the arrow 71 in FIG.1A. Now, coatings 180 containing the second reactive component of thesecond reactive system respectively underlie and are in contact withcoatings 190 of sheets 12, 16 and 14 which include the first reactivecomponent of the second reaction system. Upon impact by a stylus ormachine key in the direction of arrow 71 as shown in FIG. 1A, a mark 26is immediately impressed on the surface of sheet 12 and the capsulescontaining a first reactive component of the second reactive system areruptured so that the liquid fill thereof spills out to contact andco-react with the second reactive component of the second reactivesystem contained in corresponding coatings 180. Therefore, images ormarks 27 are produced on the coatings 180 of the correspondingunderlying sheets 16, 14 and 11. Sheet 12 of set 10A therefore has marks25 and 26 on opposite sides thereof, each sheet 14 and 16 has marks 25and 27 on opposite sides thereof and sheet 11 has marks 24 and 27 on itsopposite sides.

In FIG. 1, manifold set 20 comprises a top sheet 28, a bottom sheet 31and an intermediate sheet 29. The top sheet is coated on its front andon its back with coatings 21a and 21b, each of which contains the firstreactive component of the first reactive system. Bottom sheet 31 hascoatings 78a and 78b on its opposite sides, each of which contains thesecond reactive component of the second reactive system. Intermediatesheet 29 carries coatings 19a and 19b on its respective opposite sides.Each coating 19a and 19b comprises an admixture of the second reactivecomponent of the first system and the first reactive component of thesecond reactive system, which components are not chemically compatibleto react to produce a color. The pressure of a stylus or machine keyimpressed on the top surface of sheet 28 in the direction of arrow 72immediately imprints a mark 32, the image of which is transferred ontothe top surfaces of underlying sheets 29 and 31 as markings 33. Thesheets of set 20, similarly, as in the earlier described embodiment, areactually in face-to-face contact, and the fill comprising the firstcomponent of the first system which is contained within themicrocapsules of coating 21b is spilled from the ruptured capsules uponimpact by the key or stylus so as to contact and co-react with thesecond reactive component of the first reaction system in the uppercoating 19a of sheet 29. Likewise, the microcapsules which contain thefirst reactive component of the second reactive system and which areadmixed in the coating layer 19b on the lower surface of sheet 29 areruptured upon impact by the key or stylus so that the fill containedtherein spills out to contact and co-react with the reactive materialcomprising the second component of the second system in upper coating78A of bottom sheet 31.

For producing images on the reverse side of the sheets, each sheet 28,29 and 31 is turned upside down to present the set 20A of FIG. 2A. Amark 34 is then impressed directly upon the now upper layer 21b of theform by a stylus or machine key applying pressure in the direction ofthe arrow 73. An image 35 of the mark is created on surface 19b of sheet29 as the first reactive component of the first reaction system ofcoating 21a spills from the ruptured microcapsules to contact andco-react with the second reactive component of the first reaction systemin coating 19b. As before, microcapsules in coating 19a are rupturedupon impact, and the contents thereof comprising the first component ofthe second system spills out to contact and co-react with the chemicallycompatible second component of the second system in coating 78b of sheet31 thereby forming another mark 35. Accordingly, sheet 28 has marks 32and 34 on opposite surfaces thereof while sheets 29 and 31 have markings33 and 35 on opposite surfaces thereof.

In the FIG. 3, embodiment, a manifolded set 30 of carbonless papersheets is shown as comprising a top sheet 36, a bottom sheet 37 andintermediate sheets 38 through 43 lying therebetween. Again, each of thesheets are in face-to-face contact with one another; however, the sameare shown as being spaced for improved clarity. Here, sheet 36 has aback coating 18a, sheet 37 has a front coating 18b, sheet 39 hascoatings 18c and 18d on opposite sides thereof, and sheet 42 hascoatings 18e and 18f on opposite sides thereof. Each of the coatings 18athrough 18f comprise the second reactive component of the first reactionsystem. intermediate sheets 38, 41 and 43 respectively have backcoatings 44a, 44b and 44c thereon comprising microcapsules containingthe first reactive component of the first reaction system. Therefore,upon impact by a stylus or machine key in the direction of the arrow 74,a mark 45 is impressed on the upper surface of sheet 36, microcapsulescontaining the reactive component in coating 44a are ruptured andco-react with the reactive component in coating 18c whereby the reactivecomponent spills out to contact therewith. Likewise, the reactivecomponents from coatings 44b and 44c react with the reactive componentsin layers 18e and 18b respectively. Images 46 of the mark are therebyproduced on each of sheets 39, 42 and 37. Since the top surfaces ofsheets 38, 41 and 43 are uncoated, no image is transferred onto thesesurfaces. It should be appreciated that the sheets of set 30 in FIG. 3have been described as containing the co-reactants of the first systemonly; however, they could similarly be likewise coated in a similarmanner with the co-reactants of another initially colorless colorforming system. Moreover, additional intermediate sheets constructed inthe same manner as sheets 42 and 43 could be used with this set, and, asfew as three sheets, such as, for example, sheets 36, 38 and 37 could beused without departing from the teachings of the invention shown by thisembodiment.

To facilitate a transfer of images on the reverse sides of the markedsheets of FIG. 3, sheets 38, 41 and 43 are first turned upside down andthereafter the entire manifolded set is likewise turned upside down topresent set 30A useful for marking the reverse sides of sheets 37, 42,39 and 36 as shown in FIG. 3A. Here, upon impact with what is now theupper surface of sheet 37 by means of a stylus or machine key in thedirection of arrow 75, a mark 47 is immediately impressed upon sheet 37and images 48 thereof are transferred to sheets 42, 39 and 36respectively as the microcapsules in coatings 44c, 44b and 44a areruptured whereby the fill thereof spills out to contact and react withthe co-reactive components in the respective underlying coatings 18f,18d and 18a. As a result, sheet 37 has marks 46 and 47 on its oppositesides while the opposite sides of sheet 36 have marks 45 and 48 thereon.Each of the intermediate sheets 42 and 39 has marks 46 and 48 on itsopposite surfaces.

Manifolded set 40 shown in FIG. 4 makes use of only a single system ofco-reactants. Top sheet 49 has coatings 44d and 44e on its oppositesurfaces comprising capsules containing the first reactive component ofthe reaction system while bottom sheet 51 has coatings 18g and 18h onits opposite surfaces comprising the second reactive component of thereaction system. A mark 52 may be impressed upon the surface of layer44d of sheet 49 by means of a stylus or machine key moving in thedirection of the arrow 76, and such mark is imaged as mark 53 on the topsurface of sheet 51 as the microcapsules in coating 44e rupture and thefill thereof spills out to contact and co-react with the co-reactivecomponent in coating 18g of sheet 51.

Sheets 49 and 51 are then separately turned upside down so that coatings44d and 18h are facing one another to thereby present set 40A asillustrated in FIG. 4A, to facilitate the production of markings on theopposite sides of the sheets 49 and 51. The co-reactants in thecontacting coatings 44d and 18h of the sheets co-react to produce animage 55 on sheet 51 as a mark 54 is impressed on sheet 49 by a stylusor machine key applying pressure in the direction of the arrow 77.Again, the microcapsules in coating 44d rupture so that the fillcontained therein spills out to contact and co-react with theco-reactive material in coating 18h.

It should be pointed out that in each of the embodiments wherein one ormore sheets or sets are turned upside down, the turning takes placeabout an axis perpendicular to the plane of the drawings.

Those precursors useful in connection with carbonless copying systemsare varied and known to those having ordinary skill in this art. As anexample, particular reference is made to the color precursors mentionedin U.S. Pat. No. 3,455,721 to Phillips, Jr. et al, and particularly tothose listed in the paragraphs bridging columns 5 and 6 thereof. Thesematerials are capable of reacting with a CF coating containing an acidicmaterial such as the acid-leached bentonite-type clay disclosed in acommonly owned U.S. Application of Baxter, Ser. No. 125,075, filed Mar.17, 1971 (the entirety of which is hereby specifically incorporated byreference), or the acid-reactant organic polymeric material disclosed inthe Phillips, Jr., et al U.S. Pat. No. 3,445,721. It should be pointedout also that there are a great number of patents which relate toinitially colorless color precursors useful in connection withcarbonless copying systems. The present invention in no way depends onthe exact identity or nature of the reactants utilized except that atleast one system of co-reactants is required for two of the presentlydisclosed embodiments, and that at least two non-compatible systems ofco-reactants are required for another two of the disclosed embodiments.When a single system is used, the two co-reactants are of coursechemically compatible to produce a color. Where two systems areutilized, the first reactive component of the first reaction system mustbe chemically incapable of reacting with the second reactive componentof the second reaction system to produce a color and the first reactivecomponent of the second reaction system must likewise be chemicallyincapable of reacting with the second reactive component of the firstreaction system to produce a color. Manifestly the first and secondreactive components of the first system are chemically reactive to forma color and likewise the first and second reactive components of thesecond reaction system are chemically reactive to form a color.

For one of these systems, any of the materials disclosed in the U.S.Pat. No. 3,445,721 referred to above, which are capable of undergoing anacid-base type reaction with an acidic material, may be utilized. Alsooperable in connection with this first system are the spirodipyrancompounds disclosed in the U.S. Pat. No. 3,293,060 to Harbort, withspecific reference being made to the disclosure of this patent in column11, line 32 through column 12 line 21. Particularly useful colorprecursors are disclosed in the patents to Davis, U.S. Pat. Nos.3,193,404, 3,278,327 and 3,377,185. The color precursors of Harbort aswell as those of Phillips, Jr. et al and Davis are initially colorlessand are capable of becoming highly colored when brought into contactwith an acidic material such as an acid activated bentonite clay or anacid-reacting polymeric material, or the like. The Harbort, Phillips,Jr. et al and Davis disclosures are specifically incorporated herein byreference, although there are any number of similar color precursorscapable of undergoing a reaction with an acidic coating to produce acolor which are usable herewith.

In general, the color presursor materials of the Phillips, Jr. et al,the Harbort and the Davis patents may be dissolved in a solvent and thesolution may be encapsulated as taught in the Macaulay U.S. Pat. No.3,046,308 and the Green U.S. Pat. No. 3,712,507 patents mentionedhereinabove. Other processes for encapsulating color precursors aredisclosed in U.S. Pat. No. 3,429,827 to Ruus and in U.S. Pat. No.3,578,605 to Baxter. In this connection, it should be pointed out thatthe exact nature of the capsule itself is not critical so long as thesame is capable of containing the color precursor with the capsulescapable of being ruptured upon impact in accordance with theconventional carbonless copying procedures. Solvents which are useful inconnection with dissolving color precursors include chlorinatedbiphenyls, vegetable oils (castor oil, coconut oil, cottonseed oil,etc.), esters (dibutyl adipate, dibutyl phthalate, butyl benzyl adipate,benzyl octyl adipate, tricresyl phosphate, trioctyl phosphate, etc.),petroleum derivatives (petroleum spirits, kerosene, mineral oils, etc.),aromatic solvents (benzene, toluene, etc.), silicone oils, or anycombinations of the foregoing. Particularly useful are the alkylatednaphthalene solvents disclosed in U.S. Pat. No. 3,806,463 to Konishi etal.

With regard to the acidic coatings capable of converting the colorprecursors into their highly colored form, particular reference is madeto the clay coatings disclosed by Baxter in application Ser. No. 125,075referred to above.

In each of the above mentioned color-forming systems, it is conventionalfor the color precursors to be contained in pressure rupturablemicrocapsules which are coated on the backs of the sheets of carbonlesscopying manifolded sets. Also, the acidic coatings are normally coatedon the fronts of the sheets with the color precursor material in asolvent therefor being transferred from an adjacent back coating to theacidic layer front coating upon rupture of the adjacent capsules whichcontain the color precursor material.

For examples of a second initially colorless reaction system wherein thereactive components are chemically non-reactive with the acid-base typereactants of the systems, described above, reference is made to thepatents to Ostlie, U.S. Pat. No. 3,481,759, Matson, U.S. Pat. No.3,516,846 and Matson, U.S. Pat. No. 3,516,941. The sysems disclosed inthese patents include a dithiooxamide compound as one component and ametal rosinate, particularly nickel rosinate, as the other component. Ingeneral, the dithiooxamide material is incorporated into a suitablesolvent therefor, such as cyclohexane, and is microencapsulated. Therupturable microcapsules containing the dithiooxamide fill material arethen utilized as the pack coating in a carbonless copying system. Themetal rosinate salt is used as a front coating and the two materialsreact to present a clear mark. The color systems disclosed in the OstlieU.S. Pat. No. 3,481,759 and in the Matson 3,516,846, and 3,516,941patents referred to above are quite useful in connection with thepresent invention in combination with the systems disclosed in thePhillips, Jr. et al U.S. Pat. No. 3,445,721, the Harbort U.S. Pat. No.3,293,060, and the Davis U.S. Pat. Nos. 3,193,404, 3,278,324, and3,377,185 patents in view of the fact that the Phillips, Jr. et al, theHarbort and the Davis color precursors are not reactable with metallicrosinates to form a color and the dithiooxamides of Ostlie and Matsonare not reactable with acidic layers, such as of acid-leachedbentonite-type clay or acidic polymeric materials, for imagedevelopment. Other patents which disclose dithiooxamide color-formingsystems are U.S. Pat. Nos. 3,287,154, 3,437,677 and 3,558,341.

Other initially colorless color forming systems which may be useful inconnection with the present invention include an alkali metalgallate-iron lactate salt system as disclosed in U.S. Pat. No.2,870,040; a system wherein an acid ester substituted polyhydric phenolis reacted with an iron or vanadium compound to produce a highly coloredchelated compound as disclosed in U.S. Pat. No. 3,535,139; a systemwherein an organovanadium compound is reacted with an aromatic hydroxycompound as disclosed in U.S. Pat. Nos. 3,592,677 and 3,632,617; systemswherein phloroglucinol, 3-hydroxyphenyl urea, aniline hydrochloride,4-aminophenylglycine hydrochloride, N,N-dimethyl-p-phenylenediaminehydrochloride, 3-aminopyridine, skatole, 3,4-dimethyl-5-pyrazolone,2-methylindole, or cobalt thiocyanate is reacted with lignin to form avisible reaction product as disclosed in U.S. Pat. No. 3,450,553; andsystems wherein an alkali metal or ammonium iodide solution is appliedto a surface containing a color forming iodine-reactive substance and anagent for releasing iodine from the iodine solution, as disclosed inU.S. 3,677,786. Another system which has been found to be operable inaccordance with the present invention in connection with a Lewisacid-Lewis base reaction system is a system wherein diphenyl carbazideis reacted with nickel stearate.

With respect to the specific embodiments of the present invention,coatings 210 in FIGS. 1 and 1A, coatings 21a and 21b in FIGS. 2 and 2Aand coatings 44a through 44e in FIGS. 3, 3A, 4 and 4A may includemicrocapsules containing a fill material comprising, as the firstinitially colorless reactive component of a first initially colorlessreaction system, a color precursor selected from among those disclosedin U.S. Pat. Nos. 3,455,721, 3,293,060, 3,193,404, 3,278,327 and3,377,185 discussed above. Coatings 190 of FIGS. 1 and 1A, coatings 19aand 19b of FIGS. 2 and 2A and coatings 18a through 18h of FIGS. 3, 3A, 4and 4A may include, as the second reactive component of such firstreaction system, a color-forming reactive material such as theacid-treated bentonite-type clay disclosed in Baxter's application Ser.No. 125,075 or the acidic polymeric materials disclosed in U.S. Pat. No.3,455,721.

Coatings 190 of FIGS. 1 and 1A and coatings 19a and 19b of FIGS. 2 and2A may also comprise, in admixture with the acidic reactive components,microcapsules containing a liquid fill including, as the first initiallycolorless reactive component of a second initially colorless reactionsystem, a dithiooxamide material of the sort disclosed in U.S. Pat. Nos.3,516,846 and 3,516,941 mentioned above. The second reactive componentof the second reaction system is included in coatings 180 of FIGS. 1 and1A and coatings 78a and 78b of FIGS. 2 and 2A. This component maycomprise, for example, a metallic rosinate salt.

As pointed out earlier, it is critical to the invention that the firstand second components of the first system be chemically compatible forimage development and that the first and second components of the secondsystem be likewise chemically compatible for image development. However,the first component of the first system and the second component of thesecond system must not be capable of reacting to form a color andlikewise, the first component of the second system and the secondcomponent of the first system must not be capable of reacting to form acolor. Other than this, the sole basis for choosing between one oranother of the various chemical reactants disclosed above is the colordesired in the final copy produced by the colorless copying system.

As a specific example of the color forming materials used with thepresent invention, coatings 210, 21a, 21b and 44a through e preferablycomprise an encapsulated solution of p-toluene sulfinate of Michler'shydrol in a suitable solvent therefor. The acidic color forming reactivecomponent of coatings 190, 19a, 19b and 18a through 18h preferablycomprises the acid-treated bentonite-type clay material disclosed byBaxter in application Ser. No. 125,075.

The microcapsules included in coatings 190, 19a and 19b preferablycontain, as the first reactive component of the second reaction system,a dithiooxamide material as described in Example 18 of U.S. Pat. No.3,516,846. This dithiooxamide material is dissolved in an appropriatesolvent as is also described in Example 18 of the U.S. Pat. No.3,516,846. The intended capsule fill material is then microcapsulatedand the microcapsules are coated onto a sheet of paper in accordancewith Example 19 of this same patent. Coatings 180, 78a and 78bpreferably comprise nickel rosinate which has been coated on therespective sheets by forming a solution of nickel rosinate which isapplied to the sheets and the solvents removed by drying to leave therequired residue. This procedure is also described generally in Example18 of said U.S. Pat. No. 3,516,846.

Coatings 190, 19a and 19b in the FIGS. 1, 1A, 2 and 2A preferablyinclude both the microencapsulated dithiooxamide material describedabove and the acid-treated bentonite-type clay material describedearlier. In the production of coatings 190, 19a and 19b, themicrocapsules may first be applied to the appropriate surface of sheets12, 14 and 16 and to each surface of sheet 29. Thereafter, a slurry ofacid-treated bentonite-type clay may be applied to this microcapsularcoating and allowed to dry.

In view of the foregoing, it can be seen that a simple and economicalyet highly effective manifolded set of carbonless copying papers is setforth in several embodiments, each of which is capable of having imagesproduced on opposite sides of its sheets.

Obviously, many modifications and variations of the invention are madepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

I claim:
 1. A manifold set of carbonless recording sheets, comprising:astack including at least two superimposed sheets; each of said sheetshaving on each of its surfaces, a coating comprising an initiallycolorless color forming reactive component, a reactive component of eachof the coatings of one of said sheet being .Iadd.in a transferable formsuch that the same will be transferred from said one sheet to anadjacent sheet in response to application of pressure to said stack andbeing .Iaddend.capable of reacting to produce a colored mark with areactive component of each of the coatings of a second of said sheetsupon coming into reactive contact therewith, .Iadd. said reactivecomponent of each of the coatings of said second sheet being in anon-transferable form such that the produced mark is presented on saidsecond sheet, .Iaddend. said one sheet being disposed in overlyingrelationship to said second sheet such that one of its coatings isdisposed against one of the coatings of said second sheet, whereby uponapplication of pressure to said stack, said one coating of said onesheet is forced into said reactive contact with said one coating of thesecond sheet to thereby produce a colored mark, said sheets beingcapable of rearrangement such that said one sheet overlies said secondsheet with its other coating disposed against the other coating of thesecond sheet, whereby upon application of pressure to said stack saidother coating of said one sheet is forced into said reactive contactwith said other coating of the second sheet to thereby produce anothercolored mark. .[.2. A manifold set as set forth in claim 1 wherein eachof the coatings of a first of said sheets comprises a plurality ofpressure rupturable microcapsules containing said color forming reactivecomponent thereof, said microcapsules being rupturable upon applicationof said pressure to said stack..].
 3. A manifold set as set forth inclaim 1 wherein each of the coatings of said one sheet comprises aplurality of pressure rupturable microcapsules containing said colorforming reactive component thereof, said microcapsules being rupturableupon application of said pressure to said stack. .[.4. A manifold set ofcarbonless recording sheets comprising:a stack including at least threesuperimposed sheets; the initially uppermost and the middle sheets eachhaving a coating on their respective back surface, and the initiallylowermost sheet having a coating on its front surface, said coatingseach comprising an initially colorless color forming reactive component,a reactive component of the coating of the uppermost sheet and thelowermost sheet being capable of reacting to produce a colored mark witha reactive component of the coating of said middle sheet upon cominginto reactive contact therewith, said middle sheet being initiallydisposed in overlying relationship to said lowermost sheet such that itsback coating is disposed against said front coating of the lowermostsheet, whereby upon application of pressure to the stack, said backcoating of the middle sheet is forced into said reactive contact withthe front coating of the lowermost sheet to thereby produce a coloredmark, said sheets being capable of rearrangement such that said middlesheet overlies said initially uppermost sheet with said back surface ofthe middle sheet disposed against said back surface of the initiallyuppermost sheet, whereby upon application of pressure to the stack, saidback coating of the middle sheet is forced into said reactive contactwith the back coating of the intially uppermost sheet to thereby produceanother colored mark..]. .[.5. A manifold set as set forth in claim 4wherein the coating of at least one of said sheets comprises a pluralityof pressure rupturable microcapsules containing a color forming reactivecomponent thereof, said microcapsules being rupturable upon applicationof said pressure to said stack..]. .[.6. A manifold as set forth inclaim 4 wherein the coating of said middle sheet comprises a pluralityof pressure rupturable microcapsules containing a color forming reactivecomponent thereof, said microcapsules being rupturable upon applicationof said pressure to said stack..].